This thread is not for speculation or discussion (except as it related to establishing source material). We have MCT Speculation threads for that, but with hundreds of pages, actual source material gets lost in the speculation.

"The final piece of the puzzle for figuring out the Mars architecture is a methane engine. You need to be able to generate the propellant on the surface. Most of the fuel used in rockets today is a form of kerosene, and creating kerosene is quite complex. It’s a series of long-chain hydrocarbons. It’s much easier to create either methane or hydrogen. The problem with hydrogen is it’s a deep cryogen. It’s only a liquid very close to absolute zero. And because it’s a small molecule you have these issues where hydrogen will seep its way through a metal matrix and embrittle or destroy metal in weird ways. Hydrogen’s density is also very porous, so the tanks are enormous and it’s expensive to create and store hydrogen. It’s not a good choice as a fuel.“Methane, on the other hand, is much easier to handle. It’s liquid at around the same temperature as liquid oxygen so you can do a rocket stage with a common bulkhead and not worry about freezing one or the other solid. Methane is also the lowest-cost fossil fuel on Earth. And there needs to be a lot of energy to go to Mars.“And then on Mars, because the atmosphere is carbon dioxide and there’s a lot of water or ice in the soil, the carbon dioxide gets you CO2, the water gives you H2O. With that you create CH4 and O2, which gives you combustion. So it’s all sort of nicely worked out.“And then one of the key questions is can you get to the surface of Mars and back to Earth on a single stage. The answer is yes, if you reduce the return payload to approximately one-quarter of the outbound payload, which I thought made sense because you are going to want to transport a lot more to Mars than you’d want to transfer from Mars to Earth. For the spacecraft, the heat shield, the life support system, and the legs will have to be very, very light."

Chris Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

I am Elon Musk, CEO/CTO of a rocket company, AMA! ElonMuskOfficial 5 months ago Actually, we could make the 2nd stage of Falcon reusable and still have significant payload on Falcon Heavy, but I think our engineering resources are better spent moving on to the Mars system.MCT will have meaningfully higher specific impulse engines: 380 vs 345 vac Isp. For those unfamiliar, in the rocket world, that is a super gigantic difference for stages of roughly equivalent mass ratio (mass full to mass empty).

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ElonMuskOfficial 5 months ago Default plan is to have a sea level and vacuum version of Raptor, much like Merlin. Since the booster and spaceship will both have multiple engines, we don't have to have fundamentally different designs.This plan might change.

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At first, I was thinking we would just scale up Falcon Heavy, but it looks like it probably makes more sense just to have a single monster boost stage.

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Goal is 100 metric tons of useful payload to the surface of Mars. This obviously requires a very big spaceship and booster system.

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The Mars transport system will be a completely new architecture. Am hoping to present that towards the end of this year. Good thing we didn't do it sooner, as we have learned a huge amount from Falcon and Dragon.

(Question about Raptor)

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Thrust to weight is optimizing for a surprisingly low thrust level, even when accounting for the added mass of plumbing and structure for many engines. Looks like a little over 230 metric tons (~500 klbf) of thrust per engine, but we will have a lot of them

« Last Edit: 06/18/2015 03:01 AM by Robotbeat »

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Chris Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

“We’re looking at our Mars transporter being around 15 million pounds of thrust,”

(I think this is around 2014? Can someone else date this for me? The date is important because MCT/BFR/Raptor have clearly being evolving since Musk first started talking about them...)

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Chris Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

I mean, if you do a densified liquid methalox rocket with on-orbit refueling, so like you load the spacecraft into orbit and then you send a whole bunch of refueling missions to fill up the tanks and you have the Mars colonial fleet - essentially - that gets built up during the time between Earth-Mars synchronizations, which occur every 26 months, then the fleet all departs at the optimal transfer point.

Here are my notes from about a year ago (some duplication with the information above):

we started hearing about Elon Musk's aims as regards to sending humans to Mars. On 20th March 2012 he told the BBC [http://www.bbc.co.uk/news/health-17439490] "Land on Mars, a round-trip ticket - half a million dollars. It can be done,", not initially but as a long term aim for a mature system.

"My vision is for a fully reusable rocket transport system between Earth and Mars that is able to re-fuel on Mars - this is very important - so you don't have to carry the return fuel with you when you go there," he told the BBC."The whole system is reusable, every bit - nothing is thrown away. That's very important because then you're just down to the cost of the propellant. And then of course the smart move is pick the propellant that is the lowest energy cost.” The system seems to consist of a large launch vehicle and a spaceship which carries people between earth orbit and Mars. This launcher is currently unnamed but often called the Big Falcon Rocket, the spaceship is called the MCT, which stands for Mars Colonial Transporter.

By November 2012 [http://shitelonsays.com/transcript/elon-musk-interview-at-the-royal-aeronautical-society-2012-11-16] he told Royal Aeronautical Society in London that he envisaged a colony of 80,000 people, but that initially the pioneering group would be fewer than 10 people. In a later Twitter Elon clarified this “Millions of people needed for Mars colony, so 80k+ would just be the number moving to Mars per year”

The MCT would not be a cycler or carry a Dragon capsule instead he told SPACE.com [http://www.space.com/18596-mars-colony-spacex-elon-musk.html] “I think you just land the entire thing.”

“To establish life on Mars I think that you really ultimately need to be able to carry millions of people there and millions of tonnes of cargo. So you really need a fully reusable Mars transportation system which is yet a more difficult step than creating a fully reusable Earth system.” Elon Musk told the 15th Annual International Mars Society Convention [https://www.youtube.com/watch?feature=player_embedded&v=9blyqTwX44E]

On 9th December 2013 Elon Musk told Dr Crystal Dilworth [https://www.youtube.com/watch?v=diFftgLbsDI] “Mars is, if you have a low energy trajectory, like a minimum energy trajectory is about 6 months. I think that can be compressed down to about 3 months, and it gets exponentially harder as you go lower than that - 3 to 4. It's important to actually be at that level because then you can send your spaceship to Mars and then bring it back on the same orbital synchronization. Earth and Mars synch up every two years and then they're only kinda in synch for about 6 months. Then, you know, they're really too far apart. So you've got to be able to go there and back in one go. That's important for making the cost of travelling to Mars an affordable amount.”

On 19th February 2014 Tom Mueller told a crowd at the “Exploring the Next Frontier: The Commercialisation of Space is Lifting Off” event talking of the BFR said “It's going to put over 100 tons of cargo up to Mars. That's what it takes to get to Mars”. Elon told Joseph Gordon-Levitt on his 3rd February 2014 show “HitRECord on TV” that “It would be about 100 times the size of a large SUV “ and that it would be capable of transporting 100 people at a time.

Before any manned landing several cargo flights might be needed, Gwynne Shotwell told the Space Show [http://archived.thespaceshow.com/shows/2212-BWB-2014-03-21.mp3] that the MCT “"would have to throw a bunch of stuff before you start putting people there. ... It is a transportation system between Earth and Mars.", When asked when SpaceX Mars missions would happen, she said “Lots of work to do, Elon says 12-13 years, will shoot for that timeframe”

[http://www.nasaspaceflight.com/2014/03/spacex-advances-drive-mars-rocket-raptor-power/] The Big Falcon Rocket, also known as the BFR and Falcon X is thought to have a 10m diameter and 9 Raptor liquid methane/oxygen engines with about 450 metric tons (tonnes) of thrust each. In an expendable configuration it would have a payload of 150-200 tonnes to Low Earth Orbit (LEO), if both first and upper stage where reusable payload would be 75-100 tonnes to LEO. Including the upper stage the Inserted Mass in LEO (IMLEO) would be 125-150 tonnes.

In the Gwynne Shotwell interview on the Space Show last year, she answered a question about the challenges for SpaceX in 10 or 11 years.

"We should have really great progress on our Mars vehicles." The challenges are "Turning those R&D vehicles into production vehicles, finding enough launch sites where you can get a lot of people moving, or at least planning for the launch sites to get a lot of people moving, and launching.".

So I've been looking over all the older videos where Musk talks about Mars, and I found a couple interesting bits in his talk at AIAA 2011. Keep in mind, this is "old" and plans change, but I think there is some useful information.

At 24:00, Elon talks about solar electric propulsion as an accelerator for MCT.

At 32:30, Elon talks about widening the departure window for Mars, or alternatively placing MCTs in highly elliptical parking orbits throughout the 26 month gap.

Raptor directly contributes to the rapid advancement of oxygen-rich and full-flow staged combustion and additive manufacturing technologies for the United States—enhancing U.S. industrial capability. Further, the engine enhances state-of-the-art, high-performing EELV-class propulsive capabilities for future flight engine systems to support commercial and NSS applications in accordance with Fiscal Year 2015 National Defense Authorization Act (FY15 NDAA), Section 1604. The flexibility of the Raptor design enables the technology to be applied to existing EELV-certified launch vehicles.

That last sentence hints that Raptor might be used for a Falcon-class (EELV) rocket, in addition to the BFR.

EDIT: And yes, this may be just referring to possibilities, not actual plans; keeping the door open in case the government wants to drop dollars in SpaceX's lap. But let's keep the discussion on the discussion thread, I'm just posting the words as they came from the horse's mouth here.

re 3D printing of engine components: - big cost-reduction technology for SpaceX; - print integral cooling channels in thrust chamber nozzles; - use titanium inconel alloy; - printing allows them to make things that cannot be made by any other means ==> lighter and cheaper than traditional means

For the "next-generation engine": - deep-cryo methalox engine on Raptor, cooling both methane and LOX to near theirfreezing points, rather than near their boiling points, as is typical; - "trying to print as much as possible"; - biggest limitation is the size envelope; limitation on size of the components. - can print turbopump components and many of the critical parts of the injector - helps with speed of development (avoid casting interations of several months)

Re arguments from authority on NSF: "no one is exempt from error, and errors of authority are usually the worst kind. Taking your word for things without question is no different than a bracket design not being tested because the designer was an old hand.""You would actually save yourself time and effort if you were to use evidence and logic to make your points instead of wrapping yourself in the royal mantle of authority. The approach only works on sheep, not inquisitive, intelligent people."

I don't think the Moon is a necessary step, but I think if you've got a rocket and spacecraft capable of going to Mars, you might as well go to the Moon as well - it's along the way. That's like crossing the English Channel, relative to Mars. So, it's like, if you have these ships that could cross the Atlantic, would you cross the English Channel? Probably. It's definitely not necessary, but you'd probably end up having a Moon base just because, like, why not, ya know. It terms of the key technologies, obviously it would be great to have some sort of fundamental new thing that's never existed before and pushes the boundaries of physics, that'd be great, but as far as the physics that we know today, I actually think we've got the basic ingredients - they're there. I mean, if you do a densified liquid methalox rocket with on-orbit refueling, so like you load the spacecraft into orbit and then you send a whole bunch of refueling missions to fill up the tanks and you have the Mars colonial fleet - essentially - that gets built up during the time between Earth-Mars synchronizations, which occur every 26 months, then the fleet all departs at the optimal transfer point. I think we have - we don't need any sort of thing that people don't already know about, I believe. I believe we've got the building blocks, but the mass efficiency is extremely important. So, having better heat shields, that obviously are reusable.

In past talks Musk has hinted at the development of something called the “BFR” (where B stands for “big” and R for “rocket”), a heavy-lift vehicle far larger than the Falcon family of vehicles. At SpaceVision2005 Musk disclosed that the BFR, in its current iteration, would use “multiple” Merlin 2 engines. The BFR would be able to place 100 tons in low Earth orbit, putting it in competition with NASA’s planned shuttle-derived heavy-lift launcher. The BFR is so big, Musk said, that it’s too large for the BFTS at their Texas test site...

Direct quote from Elon implying no second stage, just booster and mars spacecraft from an article in GQ:

"Well, there's two parts of it—there's a booster rocket and there's a spaceship. So the booster rocket's just to get it out of Earth's gravity because Earth has quite a deep gravity well and thick atmosphere, but the spaceship can go from Mars to Earth without any booster, because Mars's gravity is weaker and the atmosphere's thinner, so it's got enough capability to get all the way back here by itself. It needs a helping hand out of Earth's gravity well. So, technically, it would be the BFR and the BFS." As in "Big frakking Spaceship."

Shotwell mentioned about BFR a few months ago at the South Summit 2015 (Oct 7-9), in Madrid, " [Falcon Heavy] This one is about 4M pounds of thrust, and the mock... the vehicle that takes us to Mars will be three or four times that size"

(original video, mostly Spanish-language conference proceeding, but Shotwell's voice still appears beneath a title graphic for the first ten minutes, though not her face. The video I linked above seems to have been created a while after this one was promoted, and does a proper cut to her presentation alone)

I also vaguely remember her mentioning offhand that they were developing a 180-210t to LEO superheavy launcher. I've been trying to find the interview, but can't turn anything up.